Page:Scientific results HMS Challenger vol 18 part 2.djvu/736

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Definition.— with a spongy spherical shell, the thickened wall of which is composed of a loose spongy framework.

Definition.— with a spongy spherical shell, the thickened wall of which is composed of a loose spongy framework, and exhibits a smooth surface, without radial spines and pyramidal elevations.

The genus Sagmarium, and the following two genera of Sagosphærida, represent together the subfamily Sagmarida, differing from the preceding Sagenida in the spongy structure of the shell-wall. Whilst in the latter the thin wall of the delicate spherical shell is composed of a simple lattice-plate with triangular meshes, in the former numerous branches diverge from the nodal points of these meshes, and produce by union an irregular and loose spongy framework. The surface of this spongy hollow sphere (similar to Plegmosphæra) is in Sagmarium smooth.

1. Sagmarium spongodictyum, n. sp. (Pl. 108, fig. 2).

Spongy wall of the hollow sphere about half as thick as the radius of its cavity. Bars of the spongy framework very thin and fragile, smooth, without thorns.

Dimensions.—Diameter of the sphere 2.0 to 2.4; length of the bars 0.1 to 0.2, breadth 0.001.

Habitat.—South Atlantic, Station 333, surface.

2. Sagmarium plegmosphærium, n. sp. (Pl. 108, fig. 14).

Spongy wall of the hollow sphere about one-fourth as thick as the radius of its cavity. Bars of the spongy framework rather stout, studded with numerous small spines, which arise perpendicularly from their surface.

Dimensions.—Diameter of the sphere 1.2 to 1.5, length of the bars 0.1 to 0.16, breadth 0.004.

Habitat.—Tropical Atlantic, Station 347, surface.

3. Sagmarium trigonizon, Haeckel.

Dictyosoma trigonizon, Haeckel, 1860, Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 841.

Spongodictyon trigonizon, Haeckel, 1863, Monogr. d. Radiol., p. 459, Taf. xxvi. figs. 4, 5.

Bars of the spongy framework thin, irregularly curved, bearing scattered small crosses, which are composed of four small rods arising perpendicularly from the bars. Nodal points of the